An assembly by the so-called “flip-chip” technique usually comprises forming electrically-conductive balls on a surface of a first electronic component and forming electrically-conductive connection elements, particularly balls or connection areas, on a surface of a second component according to a predetermined connection pattern. The first component is then transferred on the second component with the balls in front of corresponding connection elements, after which the assembly is pressed and heated. The balls then deform and melt to form electric connections perpendicular to the main plane of the electronic component, generally in the form of a wafer.
The most conventional technique to form the assembly is to perform a general heating of the assembly, for example, by placing the two components under a temperature-controlled atmosphere.
However, the melting of a metal ball requires high temperatures, higher than 170° C. Now, such temperatures are not compatible with organic components, particularly components made of plastic such as PEN (polyethylene naphthalate) and PET (polyethylene terephthalate), which have lower glass transition temperatures, of 120° C. for PEN and 70° C. for PET, for example. Thus, when a plastic component is submitted to the melting temperature of the solder balls, the plastic component takes a rubbery state and strongly deforms, or even destroys.